The goal of this project is to conduct a study of the speech, voice and music perception abilities of patients who hear with combined electric and acoustic stimulation (EAS) and to relate speech, voice and music perception to underlying psychophysical abilities in the region of acoustic hearing. The goal will be met through experiments and analyses relative to 6 aims. Aim 1 is to characterize low frequency acoustic hearing in patients with residual hearing before and after implantation by assessing auditory thresholds and by obtaining estimates of nonlinear cochlear processing, frequency selectivity and temporal resolution. Aim 2 is to assess the effects of acoustic stimulation alone, electric stimulation alone and combined acoustic and electric stimulation on tests of speech, voice and music recognition. Aim 3 is to determine the relationships among the psychophysical measures of low-frequency acoustic hearing and the measures of speech, voice and music recognition. Aim 4 is to compare the performance of EAS patients, patients with unilateral implants and patients with bilateral implants on measures of speech, voice and music recognition. Aim 5 is to assess the pitch of stimulation delivered to electrodes relative to that of pure tones in the region of acoustic hearing and to relate electrical pitch to computerized radiography assessment of electrode position in the cochlea. Aim 6 is to conduct studies of filter-band-to-electrode assignments in order to assess (a) whether assigning filter-bands to electrodes based on acoustic-electric pitch matching (as in Aim 5) produces better speech recognition than a standard assignment of filter bands and (b) whether overlap in representation of low frequencies by acoustic and electric stimulation is necessary for maximum levels of performance.